Quick Concepts: Generative AI Captioning

What is AI captioning and how does it work?

AI captioning creates captions using a combination of computer vision and natural language processing to analyze an image (context, objects, relationships, actions, etc.) and describe it in coherent phrases or sentences. AI caption generators can be used to caption images, audio, and video, and may be trained or fine-tuned for specialized use cases. 

The captioning process typically involves the following steps: 

  • Preprocessing – relevant features are extracted from the given input data, often by a convolutional neural network (CNN) 
  • Encoding – extracted features are specially encoded to be understood by the captioning model 
  • Caption generation – a recurrent neural network (RNN) or transformer-based model generates captions one word at a time, using previous words, context, and training data to predict each subsequent word 
  • Evaluation – the generated captions are compared to reference captions to assess their accuracy and quality 
  • Fine-tuning – the model can be fine-tuned using reinforcement learning or adversarial training to improve and refine outputs 


What are the top use cases for AI captioning?

AI captioning is useful across many industries and for a variety of purposes. For example, it can improve media accessibility for the visually impaired, tag images for online retail businesses, photo-sharing sites, and social media, automate and improve closed captioning for audio and video, and transcribe and summarize online meetings and conferences. It can also provide summaries and highlights of audio and video footage, as well as enable searchability within media. 

Benefits and limitations of AI-generated captions

AI captioning can be a boon to businesses and individual users because it is fast, efficient, scalable, largely accurate, and consistent in format. 

However, due to the following limitations, users should exercise caution and include human monitoring when using AI-generated captions: 

  • Accuracy – AI captions may contain errors of fact or interpretation, especially when presented with subtle, nuanced, or culturally-specific content. 
  • Image issues – Captions often get derailed by image issues such as poor quality/clarity, unusual objects, or abstract/highly stylized depictions. 
  • Insufficient training data/specialized content – An AI caption generator will only be as accurate as its training data; if it encounters new or unfamiliar information on which it has not been trained, it will not generate meaningful captions. 
  • Ethical overstepping – AI generated captions may overstep ethical boundaries by including offensive, harmful, or discriminatory language. Proper safeguards, monitoring, and ethical checks are essential when using generative AI tools. 


Generative AI has a host of capabilities that are automating and disrupting traditional processes in almost every field. AI-generated captioning is one of those extremely useful capabilities. However, it should be used with some caution, as it is as yet neither foolproof nor bulletproof. 

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